In an automobile, there are many powered devices, such as windshield wipers, headlights, dash lights and power windows and door locks, that are individually controlled by switches. Traditionally, these switches simply complete an electric circuit between the automobile battery and the device or a relay connecting the device to the battery. But in many fields, including automobiles, individual controls like that are giving way to controls that use a "microcontroller", a controller structured around a programmed signal processor (an on-board computer). In that environment, the switch is used to generate a control signal that is supplied to the microprocessor, initiating a program call that prompts the processor to execute a routine leading to a command that operates a driver that in turn activates a power relay, connecting battery power to the device. While there are many advantages with this type of control scheme in an automobile, considerably less wiring being one, there are tradeoffs. A microprocessor is a relatively sensitive piece of electrical equipment, one that is not capable of providing high power. This is the reason for the use of a relay driver. The driver, a semiconductor device, must be large enough to handle normal operating loads (coil current), but not too large, to minimize component cost. That makes drive protection particularly important because if the load changes, for example, there is a coil short, excessively high current may damage the drive when the microprocessor activates it.